Annuals are plants that need to be replaced each season. Some may live year round in warmer climates but they will not survive our winters. There are Cool season annuals and Warm season annuals. Cool season annuals are planted in early spring or fall. Summer annuals are planted in late spring or early summer. Although they do not come back every year, they provide non-stop color all season long and are a great addition to the garden.
Perennials return every year. Some are evergreen, but the majority will die to the ground after a killing freeze and return in the spring. Almost all of them will spread over time. Division can be done every few years to control spread. You will also benefit by doing this by getting extra plants!
Deadheading means cutting off dead flowers which will encourage more blooms. This will also keep the plants tidy. In some cases in is easier to shear the plants (cut back the entire plant instead of individual flowers). Cutting back means cutting the entire plant back to the ground.
Deciduous Trees and Shrubs lose their leaves in Fall and Winter.
Evergreen Trees and Shrubs retain their leaves/needles all year long, although they may shed them periodically and grow replacements.
Semi-Evergreen plants will usually retain some foliage in the winter, how much will depend on the severity of the winter, the exposure (wind is an important factor) and the establishment period (amount of time the plant has been in the ground). They will re-grow new leaves in the spring.
Limbing up means removing lower branches of trees so that the canopy of the tree is elevated. In some cases you want to do this so that the bark is exposed (in cases where the tree has attractive bark or is multi-stemmed) or for shade or flowering trees so that the lower branches are raised.